Abstract
Purpose: :
In a previous report, we showed that intravitreal injections of bacterial lipopolysaccharide (LPS), 24 h before ischemia induce late ischemic preconditioning. The aim of this study was to investigate whether LPS triggers early preconditioning and postconditioning in the rat retina.
Methods: :
Rats were intravitreously injected with 3 µg LPS in one eye and vehicle in the contralateral eye, 30 or 60 min before, or 15 or 60 min after retinal ischemia induced by increasing intraocular pressure to 120 mmHg for 40 min. Subsequently, 7 or 14 days after ischemia, rats were subjected to electroretinography and histological analysis by light microscopy of retinal sections.
Results: :
Ischemia for 40 min and reperfusion for 7 or 14 days induced a significant decrease in scotopic ERG a- and b-wave amplitude. The ischemia-induced decrease in both a- and b-wave amplitude was significantly lower in eyes injected with 3 µg LPS 60 min (but not 30 min) before and 15 and 60 min after ischemia. Moreover, histological examination revealed that ischemia-associated structural damage and loss of cells in the outer and inner nuclear layers were largely prevented by LPS injected 60 min (but not 30 min) before or 15 and 60 min after ischemia.
Conclusions: :
For the first time, these results indicate that LPS triggered early preconditioning and postconditioning in the rat retina, providing a significant functional and histological protection against ischemia/reperfusion damage.
Keywords: retina • ischemia • neuroprotection